Jet rock bit



J. B STEEN JET ROCKBIT 5 Sheets.. 1

Filed July 22, 1959 ENTQ (j /1455 BY ATTORNEY Dec. 26, 1961 J. B. STEEN3,014,544

JET'ROCK BIT Filed July 22, 1959 3 Sheets-Sheet 2 J. B. STEEN JETROCKBIT Dec. 26, 1961 3 Sheets-Sheet 3 Filed July 22, 1959 INVENTOR ATTORNEYUnited States Patent Ofiice 3,914,544 Patented Dec. 26, 1961 3,014,544JET ROCK BIT James B. Steen, Fort Worth, Ten, assignor to ChicagoPneumatic Tool Company, New York, N.Y., a corporation of New JerseyFiled July 22, 1959, Ser. No. 828,892 9 Claims. (Cl. lifi lidtl) Thisinvention relates to rotary earth boring drills and particularly to ajet arrangement for discharging a stream of drilling fluid at highvelocity on the bottom of the bore hole.

The usual rock bit of the three-cone type comprises a bit head, threelegs depending from the head and spaced 120 apart, and three spindlesinclined downwardly and inwardly from the legs to support respectivelythree cone cutters. The cutters occupy a large area over the bottom ofthe hole and do not allow much space for the discharge of a stream ofdrilling fluid from a nozzle in the bit head to the bottom of the hole.However, there is a clearance space for the jet streams to pass withoutinterference in each of three localities lying in median planesequi-distant from the spindle axes.

In the usual jet cone bit, there are three jet nozzles each arranged inone of the median planes and mounted in the head with its axissubstantially vertical so as to discharge the stream downward along themedian plane of clearance between the cutters. The stream impinges onthe bottom of the hole at a right angle thereto and disperses the rockparticles or chips in different directions. The spot where the streamstrikes the bottom of the hole is midway between the cutters, or about60 in advance of the next cutter. Some of the chips which are dislodgedby a leading cutter are washed into the path of the trailing cutter. Asa result, the cone cutters roll over a layer of loose chips at thebottom of the hole to re-grind the chips, and the cutter teeth areprevented from pene trating deeply into the earth formation.

An' object of the present invention is to improve the penetration of thecone cutters by removing the chips from the path of the approachingcutter. In accordance with this invention, the jet stream is arranged tostrike the bottom of the hole at an acute angle instead of at rightangles. Preferably, the inclination of the stream is in a leadingdirection to push the chips toward the cutter which has just dislodgedthem and away from the cutter which follows, thus confronting eachcutter with a clean surface on the bottom of the'bore hole.

In addition to the change in the angle of inclination of the jet streamon the bottom of the hole, the present invention departs from theusualpractice by changing the spot on the bottom of the hole where the streamstrikes, placing it ahead of the median plane of clearance and far aheadof the approaching'cutter so that the chips have ample time to escapefrom the bottom of the hole before the next cutter arrives.

Another object is to direct the stream toward the trailing side of acutter in approximately a tangential relation thereto, but with thestream and cutter teeth moving in opposite directions with the resultthat the chips are lifted from the bottom of the hole by the combinedeffect of the jet fluid turbulence and the churning action of the teeth.

Another object is to reposition the nozzle housing in the bit head sothat it will be more effective than previously both during the down flowand during the subsequent up flow of the drilling fluid. By tiiting thestream as previously described, it is possible to offset the nozzle andits housing with respect to the median plane of clearance between thecutters without causing interference between the cutters and the stream.This arrangement permits the nozzle housing to be located closeto onespindle for attachment to a drill string supporting leg and far awayfrom another leg, whereas in the usual jet cone bit the nozzle housinglies midway between the legs or in the median plane of cutter clearance.The offsetting of the nozzle housing permit the entire nozzle housing tobe formed integrally in one of the three segments which make up the bithead, without creating the problems which arise when the nozzle housinglies on both sides of the radial plane which separates two segments. Italso provides a greater space on the outside of the bit head for thepassage of the ascending fluid and entrained chips.

The above objects are attained Without sacrificing the advantage of anunimpeded stream. In accordance with this invention, the jet nozzle islocated above one of the cutters and spaced from the median plane ofclearance between the cutters. However, the inclination of the nozzle issuch that the stream may cross the median plane at the level where thecutters are closest to each other and then proceed to a spot on theother side of the median plane.

Other objects and features of the invention will appear more fully fromthe description which follows.

in the accompanying drawings:

FIG. 1 is an elevational view of a fragmentary portion of a bit headsegment forming part of a cone type rock bit according to one form ofthis invention, and showing the jet nozzle supported in operativeposition;

FIG. 2 is a bottom plan view of the segment and jet nozzle of FIG. l,and showing also the nozzle of the following segment;

FIG. 3 is a longitudinal section of a fragmentary part of the rock bitin the plane in the axis of the nozzle;

FIG. 4 is a development view showing portions of two of the cutters inoperative relation to the jet stream which passes between them;

FIG. 5 is a diagrammatic view showing one of the jet streams inoperative relation to the leading cutter and to the detritus or chipsdislodged by the combined cutting and jet action;

FIG. 6 is a bottom plan view of part of the rock bit of FIGS. 15 showingone-and-one-half cutters mounted thereon and two of the jet streamsissuing from the rock bit; and

FIG. 7 is a view similar to FIG. 6 but showing a modification.

In both forms of invention the jet arrangement is incorporated in a rockbit of the type which comprises a bit head made of three segmentsarranged respectively to support three cone cutters for rolling over theformation at the bottom of the bore hole'9 (FIG. 6).

Referring to FIGS. 1 and 2, the head segment 10 comprises a body portion11, a depending leg 12 and a spindle 13, all forming an integralstructure such as a steel forging or casting. The spindle supports acone cutter 14A or 14B (FIG. 6) for rotation about an individual axis15A or 15B which is inclined downward and inward, and which intersectsthe vertical axis 1670f the rock bit which latter axis forms the centerof the bore hole 9. The segment body'portion 11 extendscircumferentially for between the two lateral faces 17, each lying in avertical plane. The lateral faces preferably are in symmetrical relationto the spindle axis 15A that is to say, the plane of the spindle axisbisects the body portion 11, or is spaced 60 from either of the lateralfaces 17. The lateral faces are arranged in abutting relation to twoother identical segments. The three segments are secured together by theusualmeans, including holes l8rfor re: ceiving dowel pins (not shown)and marginal recesses 19 for receiving welding material (not shown). V

The upper part of the body portion 11 is provided at its exterior withthe usual screw threads (not shown) by means of which the rock bit maybe rotated in a clockwise direction looking downward, or in acounterclockwise direction when viewed as in FIGS. 2 and 6. At itsexterior, the upper part of the body portion is provided with a boresector 20 leading to a cavity 21. The three bore sectors combine to forma central bore which receives drilling fluid or mud. A passageway 22extends generally downward from the cavity 21 and opens at the lower endof a hollow boss 23 integral with the segment body 11. The boss isinclined downward toward the vertical plane of the adjacent lateral face17 but does not extend beyond it. The passageway 22 is suitablycounterbored and grooved to receive a nozzle 24A or 24B. The nozzlewhich is of conventional construction, is shown best in FIG. 3. For amore complete disclosure of the nozzle and its retaining means,reference is made to Payne U.S. Patent 2,855,182. Preferably, the'axisof the passageway 22 is directly in line with the axis of the nozzle 24Ato minimize any turbulence that otherwise might be caused by change ofdirection of the stream of drilling fluid as it approaches the nozzle.The nozzle is arranged to discharge a high velocity stream 25 onto thebottom of the bore hole to wash away and erode the earth formation. Theposition of the nozzle and the direction of the nozzle axis with respectto the cone cutters 14A, 143, etc., are arranged in a novel manner toproduce new results as will be pointed out later.

As seen in FIG. 6, the cones 14A and 14B, as well as the third cone, areclosely spaced with the circumferential rows of teeth of one coneinterfitting Within circumferential grooves between the rows of teeth onadjacent cones. At the outer end or heel of each cutter, however, therows of teeth do not interfit but track each other over the same annulararea. In a bit of the cone type, there is very little room for ajetstream to pass between the cutters without obstruction in order tostrike the bottom of the hole the full force. The region of maximumclearance between the cone cutters is located between the heel portionsof two cutters and in a plane which lies midway between the planes ofthe spindle axes. As seen in FIGS. 3 and 6, the median planes betweenthe spindle axes A and 15B are spaced from the latter by 60 in eitherdirection, and are designated 26A and 26B respectively. In the priorart, it is common practice to arrange the nozzle with its axissubstantially vertical and to direct the jet stream along the planes26A, 26B, and the third median plane. It has been discovered, however,that conventional nozzle arrangements do not result in maximum drillingspeed, and that improved results can be obtained by inclining the axisof the nozzle and by changing the position of the spot where the jetstream impinges on the bottom of the borehole.

For convenience of description, the point where the center of the jetstream leaves the nozzle will be designated 27 and the point where thecenter of the stream strikes the bottom of the hole will be designated28. In the prior art, the nozzle end and the bottom end of the jetstream lie substantially in the same vertical plane as the median planebetween the spindle axes. In accordance with this invention, however,the point 27 is shifted rearwardly by about while the point 28 isshifted forwardly by about 15 making a total displacement of about 35from one end of the stream to the other. The displacement of the points27 and 28 is the result of tilting the axis of the nozzle 24A or 24B sothat the stream is directly forwardly and outwardly as well asdownwardly. Both the tilting and the circumferential displacement of thenozzle are necessary in order t o attain the results of this inventionin a cone bit. If the nozzle is displaced without tilting its axis or ifthe jet stream is tilted without relocating the nozzle, the jet streamwill clash against the cutters. However, in the embodiment of FIGS. 1-6interference between cutters is prevented or at least minimized becausethe axis of the jet stream intersects the median plane 26B at a point 29which is at the level where the two cutters 14A and 14B come closest toeach other, as shown in FIG. 4. It should be understood that thecircumferential measurements 20 and 15 respectively are by way ofexample, and not limitation, and it is believed that satisfactoryresults can be obtained by displacing the nozzle end 27 of the stream 25by only 10 rearwardly of the median plane of separation between thecutters. The 20 displacement is deemed preferable because it entails agreater inclination of the jet stream.

The effect of the inclined jet stream is shown diagrammatically in FIG.5. The cutter 14A operates on the bottom of the hole with a chiselaction and removes small particles of earth formation consisting ofchips or detritus 31. These chips are entrained in the drilling fluid ormud which issues from the stream 25 and are carried outwardly at themedian plane 263 and then upwardly along the side of the bit head to thetop of the hole 9. When the drill bit is rotated at high speed, however,the chips have a tendency to remain on or near the bottom of the holeuntil the succeeding cutter 14B runs over the chips. In the prior art,the jet stream, which was arranged substantially vertical, had theelfect of scattering the chips in different directions, some of themmoving rearwardly into the path of the succeeding cutter 14B. The resultwas that the cutters continually rolled over a layer of chips whichprevented the teeth from penetrating deeply into the solid rock. Withthe arrangement of this invention, however, the stream 25 is inclined atan acute angle to the bottom of the hole, and the angle of incidence issuch that the stream now pushes all of the chips forwardly and away fromthe next cutter 1413 thus presenting the latter with a clean surface onthe bottom of the hole.

Another advantage which is believed to result from the inclination ofthe stream, and from the relocation of the spot where it strikes thebottom of the earth, resides in the turbulence imparted to the streamafter it strikes the bottom of the hole and starts moving outwardly andupwardly. As shown in FIG. 4, the stream 25 comes very close to theleading cutter 14A. In FIG. 5, the distance between the stream and thecutter is exaggerated in order to show the action more clearly. It willbe understood, however, that the cutter 14A and particularly the teethin the heel row, due to the close proximity of said teeth with thestream, have an effect of changing the course of the stream after itstrikes the ground. With this arrangement, the rebounding stream isdirected toward the cutter 14A and is then churned upward by the cutterteeth which act in the manner of a paddle wheel. The upwardly movingstream entrains the chips 31. The churning action contributes to thequick removal of the chips 31 because the latter have a higher specificgravity than the fluid in the jet stream and therefore would tend toremain on the bottom of the hole if the stream were not properlydirected.

The invention reduces the resistance to the outward passage of thechip'laden fluid from the bottom to the side wall of the hole. Referringto FIGS. 4 and 6, the position of maximum clearance between the adjacentcutters and therefore of minimum resistance to egress of chips lies inthe median plane 26B; and the spot 28 of impingement of the stream 25 isdisplaced by about 15 in advance of the clearance plane. Thisdisplacement permits the flow of a substantial quantity of chips 31following impingement and during conditions of minimum obstruction asthe rock bit advances relatively to the chips and carries the plane ofthe clearance space over the area of the loosened chips.

The invention increases the interval of time between the instant ofimpingement of a chip by the jet stream, and the instant that thesucceeding cutter arrives at the spot of impingement and this intervalis adequate to permit the chips which are dislodged by one cutter topass out Theincreased time interval is due in part to the fact that thespot of impingement 28 lies far ahead of the cutter which follows. Withthe arrangement shown, the rock bit must revolve 75 before the conecutter 1413 can reach the spot where the chip was at the instant ofimpingement, but if the loosened chip has not been carried from thebottom of the hole by that time, it will not be overtaken by the cutteruntil the rock bit has turned an additional amount corresponding to thedistance of circumferential displacement of the chip during its upwardmovement subsequent to impingement. This additional circumferentialdistance, which is a distinctive characteristic of this invention,results from the fact that the stream is inclined forwardly andcontinues swirling ahead of the approaching cutter and along with theentrained chips after the fluid has reached bottom. The stream 25,unlike the stream in the usual jet cone bits, starts its jetting actionat a circumferential speed considerably in excess of the speed ofrotation of the bit head, and if the stream has a very high velocity itmay swirl along the bottom of the hole to increase its lead on thefollowing cutter 148 before its slows down to permit the cutter toovertake the stream. In the same manner, the drilling fluid may carrythe entrained chip for a longer period of time than for 15 of bitrotation, during the period when egress is very rapid and before thechip has been overtakenby the median plane of clearance 26B. In theusual jet cone bit of the prior art, however, the interval of timebetween the instant of impingement of a chip by the jet stream and theinstant that the succeeding cutter rolls over the chip, is limited tocorrespond to about 60 of revolution of the rock bit; and during thatentire interval the egress is at'a relatively slow rate because thechips have been passedby the median plane of maximum cutter clearance.

If the jet stream is discharged at a low velocity in relation to thespeed of rotation of the rock bit, the spot of impingement 25 may besomewhat less than 15 ahead of the median plane 263, or 75 ahead of theposition 2513 of the next cutter, due to the fact that the entire rockbit advances during the interval between the time that the stream leavesthe nozzle opening 27 and the time when it strikes the bottom of thehole. However, the reduction in circumferential spacing due' to drillbit rotation is not significant because the stream in the practice ofthis invention is deliveredat a very high velocity, and for the furtherreason that the revolving nozzle imparts to the jet stream a motion oftranslation which is superimposed on the motion along the axis of thenozzle with the result that the stream tends to follow a helical courseand substantially maintain its lead over the following cutter.

The offsetting of the nozzle 24A or 24B from the median plane of cutterclearance results in another advantage because it makes possible arelocation of the spindle axis with respect to the end faces 17 of thehead segments It In the prior art, it was the usual practice to spacethe nozzles and spindles 60 apart. That arrangement necessitated thechoice between a design in which the nozzle housing on one segmentextended beyond the plane of abutment with an adjacent segment, or onthe other hand, a design in which the head segment which is otherwisesymmetrical has a lopsided spindle on Which the entire weight of therock bit and thousands of feet of superstructure are supported. Eitherone of these designs created engineering problems which have beenobviated by the nozzle of the present invention. Referring to FIG. 2,the nozzle housing 23 is spaced rather closely to the leg 12 on the samesegment and therefore is spaced widely from the leg on the adjacentsegment. The wide spacing provides a recess on the side wall of the bithead, above the spot 28, which permits free upward movement of thedrilling fluid and entrained chips FIG. 7 shows the invention as appliedto a modified type of rock bit in which the spindles are shifted so thatthe axis of rotation of each cone is askew with relation to the axis ofrevolution of the rock bit. Apart from the specific jet arrangement, theskew type of cone bit is well known in the. art and is described morefully in Garfield US. Patent 2,148,372, February 21, 1939. The modifiedrock bit 33 comprises three head segments each having a body portion 11,a depending leg (not shown) and a hollow boss 23 providing a housing fora nozzle 7 (not shown), all arranged as in FIGS. 1 and 3&

The modified spindles 34, however, are not arranged as the spindles 13but instead are mounted on axes 35 which do not intersect each other orthe axis of revolution of the bit. Each spindle supports a cutter 36having a tooth formation similar to that of the corresponding cutter14A, 143, etc., in FIG. 6. As in FIG. 6, the heel portion of the cutter36 lies approximately midway between the ends of the lateral faces 17 onthe body 11. The apex portions of the cutters 36, however, are shiftedso that they lie closer to the leading face 17 of the segment than tothe trailing face. The region of maximum clearance between the cutterslies in a plane midway between the planes of the lateral faces 17, as inthe first form of invention. The jet stream 25 is discharged in the samedirection and strikes the bottom of the holein the same spot 28 as inthe case of FIG. 6 but there is a slightly modified action of thedrilling fluid after it reaches the bottom of the hole.

In the first form of invention, the teeth on cutter 14A churn the stream25 and chips 31 upwardly as previously described and as shown in FIG. 5.In the modification of FIG. 7, however, the teeth on cutters 36, due tothe skew of the cone, appear to have the property of churning the streamand chips in a direction which is outward as well as upward.

While the invention has been described with reference to a drillingfluid of the liquid type, such as mud or slush, it is also adapted forthe use of other kinds of drilling fluid such as air or gas.

What is claimed is: v

l. A jet cone bit comprising a plurality of head segments; eachcomprising a body portion, a nozzle housing and a depending leg allintegrally formed together, each head segment having lateral facesdisposed in intersecting vertical planes apart, the segments abuttingeach other at said lateral faces, said nozzle housing being disposedadjacent one of the lateral faces and entirely on one side of thevertical plane thereof, a spindle associated with each depending leg andprojecting downwardly and inwardly therefrom, each spindle beingdisposed approximately midway between the planes of said lateral faces;a cone cutter on each of said spindles; and a nozzle mounted in saidnozzle housing and enclosed thereby around its entire circumference,each nozzle having an outlet which lies directly above the associatedcutter, said nozzle having an axis inclined circumferentially to directa stream of drilling fluid in a combined circumferential and downwarddirection with the stream passing between the cutters at a point whichis offset circumferentially from the nozzle outlet, and finally strikingthe bottom of the hole at a point closer to the cutter on an adjacentsegment than to the cutter carried by the associated segment whichsupports the nozzle.

2. A jet cone bit according to claim 1, in which the nozzle is disposednear the leading face of the head segment, and is inclined to direct thestream in a downward and forward direction across the plane of theleading face to move the detritus at the bottom of the hole forwardlyand away from the cone cutter below the nozzle.

3. In a jet cone bit, a head segment formed in one piece and comprisinga body portion, a nozzle housing and a depending leg, said head segmenthaving lateral faces disposed in intersecting vertical planes 120 apart,said head segment being disposed entirely within the region limited bysaid vertical planes, a spindle carried by the depending leg andprojecting downwardly and inwardly therefrom the spindle being disposedsubstantially midway between the planes of said lateral faces; a conecutter rotatable on said spindle, and a nozzle mounted in said nozzlehousing, said nozzle being located above said cutter with its outlet indirect vertical alinement with a portion of the cutter surface wherebysaid cutter precludes the issuance of a vertical jet stream from thenozzle to the bottom of the hole, .said nozzle having an axis inclinedcircumferentially to direct a stream of drilling fluid in a slanteddirection to by-pass the cutter and strike directly against the bottomof the bore hole.

4. A jet cone bit comprising a bit head having three depending legs, aspindle supported by each of said legs and extending downwardly andinwardly, the axes of the spindles lying in vertical planes 120 apartand intersecting each other at the axis of revolution of the bit, conecutters mounted on said spindles to cut the entire formation at thebottom of the hole, said cutters providing clearance therebetween atthree median vertical planes spaced 60 from the spindle axes, and one ormore nozzles carrid by the bit head, each nozzle being positioned abovethe forward portion of an associated cutter with its outlet offsetrearwardly from the median plane by at least 10, the axis of the nozzlebeing inclined circumferentially forward to direct the stream ofdrilling fiuid across the median plane and through the clearance spacebetween the associated cutter and the leading cutter to strike thebottom of the hole at a point closer to the leading cutter than to theassociated cutter, the stream being slanted to syeep the chips forwardlyalong the bottom of the hole out of the path of the associated cutter.

5. A jet cone bit according to claim 4, in which the vone cutters haverows of teeth in interfitting relation, the interfitting teeth beinglocated inwardly of the heel row of teeth, the latter being arranged totrack each other over a marginal area at the bottom of the hole, theaxis of the nozzle being inclined radially outward as well ascircumferentially forward to direct the stream of drilling fluid to themarginal area.

6. A jet cone bit according to claim 5, in which the nozzle axis is soinclined that the stream lies in a vertical plane substantially parallelto that of the vertical axis of the leading spindle, the angle ofincidence of the stream on the bottom of the hole being such as to blastthe chips in a forward and outward direction along the bottom of thehole.

7. A. jet cone bit comprising a bit head having three depending legs, aspindle supported by each of said legs and extending downwardly andinwardly, the axes of the spindles being askew with relation to thevertical bit axis at the center of the hole, cone cutters mounted onsaid spindles to cut the entire formation at the bottom of the hole,said cutters providing clearance thcrebetween at three regionsapproximately midway between the spindle axes, and one or more nozzlescarried by the bit head, each nozzle being positioned above one of thecutters and offset rearward from the nearest clearance region, the axisof the nozzle being inclined circumferentially forward to direct thestream of drilling fluid through the clearance space between twoadjacent cutters to strike the bottom of the hole directly withoutinterference by the cutters the angle of incidence of the stream on thebottom of the hole being such as to blast the chips forwardly andoutwardly along the bottom of the hole and thereby sweep then out of thepath of the following cutter.

8. In a jet cone bit, a head segment formed in one piece and comprisinga body portion, a hollow bOSs and a depending leg, said head segmenthaving lateral faces disposed in vertical planes radiating from the axisof rotation of the bit, a spindle connected to the depending leg and.extending downwardly and inwardly therefrom, said spindle being disposedsubstantially midway between the vertical planes of said lateral faces;a cone cutter rotatable on said spindle, said hollow boss being locatedat the leading side of the segment adjacent the leading lateral face,the lower portion of the boss providing a nozzle housing, a nozzlemounted in said nozzle housing, said nozzle being located entirely in aposition rearward of the vertical plane of the leading lateral face,said nozzle mounted with its axis slanted in a circumferentially forwarddirection to discharge a stream of drilling fluid across the verticalplane of the leading lateral face, said stream being directed to strikethe bottom of the bore hole at a point forward of the leading lateralface.

9. In a jet cone bit, a head segment according to claim 8 which includesan inlet passage above the nozzle for delivering drilling fluid thereto,said inlet passage being axially alined with the nozzle to minimizeturbulence.

References Cited in the file of this patent UNITED STATES PATENTS2,148,372 Garfield Feb. 21, 1939 2,807,444 Reifschneider Sept. 24, '19572,831,661 Brown Apr. 22, 1958

